VThethei' ElfcJridfy, Light and Cahrlc Itftniph, emptuttdeJ, ^e, 397 



ideas tlien are we to form cf the cleftric fluid and of light ? — Are they merely modifica- 

 tions of fimple caloric, or are they compounds in which caloric forms a part ? 



If the eieftric fluid be a mode of exiftence of fimple, homogeneous caloric, how are we 

 to explain the faft *, that certain ele£lric atmofpheres repel each other, which atmofpheres 

 will attra£t other ele£lric atfnofpheres that are alfo repulfive to each other ? 



It is incontrovertibly evident that cle£tric atmofpheres are of two diftinfl kinds ; equally 

 cxtenfive, equally powerful, and mutually attraftive to each other; although each is 

 invariably repulfive to every atmofpherc of the fame kind as itfelf ; and it is equally certain 

 <hat they only produce fire, or take that form when they rufli together, and ceafe to be 

 eleftric Inftead, then, of fuppofin^,' the ele6lric fluid to be caloric, or partly formed of 

 caloric, it appears to me to be more philofophical to fuppofe that it confiflis of two prin- 

 ciples t in flates of feparation, which form caloric when they quit their eleflric dates, and 

 combine. 



Is light a fimple fluid %, or a modification of caloric ? — If fo, what ingenuity can explain 

 how one homogeneous fluid, or fimple fire, can, by paffing through a prifm, be feparated 

 into fuch variety of parts fo permanently diflimilar to each other ? and how happens it that 

 light never produces fire but by evidently changing its mode of exiftence, as it ceafes to be 

 light when it takes the ftate and properties of fire ? — This confideration again feems to lead 

 to the conclufion that light confifts of diftinfi: and diflimilar principles, which, combining 

 together, iofe their properties as light, and conftitute a fluid of very different properties 

 and charafter, which we call fire, or caloric. 



Nay, even if we advert to caloric itfelf, is It an uncompounded principle, or can any 

 fimple principle polfibly perform the various parts afllgned to it ? — According to the pre- 

 fent fyftem of chemiftry, caloric, homogeneous, fimple caloric, deftroys combinations 

 which itfelf had formed ; it attaches itfelf to particles of matter, and forms itfelf into 

 repulfive fpheres around them : and yet certain fpheres of caloric in this ftate of repulfion 

 will rapidly attracD: other fpheres of the fame caloric in fimilar ftates of repulfion 1 In 

 fiiort, caloric is hot or cold, attradtive or repulfive, vifible or invifible, juft as occafion 

 may ferve ; and, Proteus-like, it takes all Ihapes and forms : — we dread to meet it in Jove's 

 thunderbolt, and court its influence in the cooling breeze 1 



« The fafts are fira^ily, that AxAVj attraft and repel each other in certain ftates of eleftrization; but the 

 exiftence of eleftric atmofpheres, of one fimple eleflric fluid, or of two, &c. are mere hypothcfcs which yet 

 remain without proof. M. de Luc (Idees fur la Meteorologie) fuppofes cleftricity to confiftof the matter of 

 heat combined with another matter incapable of paffing through glafs, &c. and that the charge is produced by 

 the condenfation of this laft with the tranfmiilion of heat, in the fame manner as fteam (water and heat) 

 might be condcnfed on a pane of glafs, and caufe the evaporation of water, fuppofed to be placed on die oppo- 

 fite furface, by virtue of the tranfmitted heat. N. 



tj- That light of every kind is emitted by the eleftric fpark is eafily feen with the prifm, N. 



X The great Leonard Euler, and others, have maintained that the fenfations and effefts of light are merely 

 confcquences of the vibrations of a rare and very elaftic fluid. To this doftrine have been oppofed the rcfti- 

 llnear motion oflight, which does not flow into the lateral fpaces, together with its refleftion, refraftion, and 

 cslours. Much complexity of vibration would indeed be required to account for thefe phenomena : but not 

 more, perhaps, than neceflarily refults from the confideration of found ; its echo, which deviates little fron\ 

 the angle of refleftion ; and the harmony, melody, tone, &c. of its diftinft cotcmporaneous and fuccefiive 

 impreffions. N. 



Vol. II.— Dec. 1798. 3 F Haying 



